Osbpl5 (Oxysterol binding protein-like 5, Obph1) lies outside of an imprinted region found in both
mouse and human extending from Ipl/IP1 to H19, a region associated with Beckwith-Weidemann syndrome
in humans. Obph1 shows predominant maternal expression in the placenta but biallelic expression in
fetal and newborn organs (Engemann
S, et al. 2000; Clark L et al, 2002). Analysis of a
CpG island 5’ to Obph1 (and more distant from the imprinted
cluster) was shown to be hypo- and not differentially methylated. These results suggest that the
Ip1/IPl to H19 imprinted region extends to Obph1 but that the CpG island 5’ to Obph1 is not
involved. Identical results were achieved in human samples (Higashimoto
K, et al. 2002).
However, Okae H et al, (2012) provided
strong evidence of negligible expression of Osbpl5 by qPCR and whole transcriptome sequencing in E
13.5 placentas. They suggest that this gene is not imprinted. This is concordant with Proudhon and Bourc'his, (2010) caution that maternal contamination of placental tissues may
cause apparent imprinted maternal expression.